Knives with mechanisms for protecting the knife blade when not in use are known. Some of these knives are of a folding variety, with a blade that pivots from an open position to a folded position where the blade is protected within an opening in the knife handle. Another variety of protecting mechanism allows for retraction of the knife blade. In this variety the knife blade can be moved from an open position which has the blade extended from the knife handle, to a closed position which has the blade disposed within an opening within the knife handle, and where the movement of the knife is substantially linear. An example of the first variety of knife is the common folding pocketknife. An example of the second variety is the common utility knife.
These knives have limitations in their use however, because they are basically gripped in the same manner. There remains a need in the art for a convenient, retractable knife that is comfortable to hold and use, and yet is suitable for cutting uses such as those for which utility knives are used. Knives are known that have blades which are substantially in line with the knife handle. Although these knives are suited to some cutting tasks, other cutting tasks are accomplished more readily with knives having blades at an angle to the knife handle. A need exists in the art for a knife that can be held in positions other than with the knife blade extending from the axis defined by a clenched fist. For cutting a sheet material such as linoleum for example, it is common to use a knife having its blade at an angle other than zero degrees to its handle. This angle allows the knife blade to be pulled through linoleum while clearance for the user's knuckles above the surface of the floor is provided. Thus, some cutting tasks are better suited to a knife with a blade in a different orientation than that found in common knives. That is, some cutting tasks would be more easily accomplished with a knife whose cutting edge would be presented in a particular orientation with respect to the hand holding the knife. Fatigue to the hand being used to hold the knife can be avoided, and safety of use can result from such a change in orientation of the blade. In particular a need exists in the art for a knife that has a blade orthogonal to the knife handle. A need also exists in the art for a knife having a blade orthogonal to its handle, and whose knife blade is also retractable. The retractable blade knife of the present invention as described herein meets these needs.
As disclosed in U.S. Pat. No. 2,359,098 to Engle, a knife is known that has a blade that is orthogonal to its handle. The blade arrangement taught in this patent does not provide for retraction of the blade, although it does provide a mechanism for adjustment to the size of a user's hand. The blade of the knife taught in this patent is always exposed, there being no retraction mechanism. The use of a knife as taught in this patent has a potential safety problem for a careless user. The knife as taught by the present invention addresses this problem by providing for retraction of its blade.
U.S. Pat. No. 1,322,775 to Fallon discloses a bladed military weapon whose blade is held in line with a user's forearm, and orthogonal to the axis of the user's clenched fist. This weapon is taught as having an extension that grips the forearm of the user. This weapon is taught as having a pivoting mechanism for the blade that allows the blade to be pivoted from a service position to a folded position above the forearm. The arrangement taught by Fallon does not provide any structure that receives a blade to protect a user against accidental cuts. Also, the weapon as taught by Fallon does not provide any means for retracting the blade of the weapon.
U.S. Pat. No. 5,025,560 to Townsend discloses an ergonomic knife that has a blade that is held orthogonal to a clenched fist of a user when in use for cutting. This knife also has a mechanism for pivoting the blade into a range of cutting positions relative to an extended support member that reaches part way up the forearm and is attached to the forearm of a user. For use, the knife disclosed requires attachment to the forearm, which can be an inconvenience and shortcoming in use. Another shortcoming is that the knife as taught by Townsend has no mechanism for retraction of its blade to a protecting position that would protect a user from accidental cuts.
Another knife having a blade orthogonal to its handle as used was disclosed in United States Design Patent D301,048 to Hollinshead. This particular knife design teaches a knife whose blade is not retractable. The blade of this knife does not extend directly to the handle, but is attached to the knife handle with two blade extension members whose attachment point to the handle are spaced apart by at least two finger widths. This knife also lacks a mechanism for retraction of its blade.
U.S. Pat. No. 4,096,629 to Levine discloses a claw weapon that has multiple retractable blades. This claw weapon has blades that while in use, project outwardly between adjoining fingers of a user's hand. The claw weapon comprises a tubular grip member that contains the blades when the blades are in a retracted position. As taught in the Levine patent, the fingers of a user are in very close proximity to the cutting edges of the multiple blades. An inadvertent shifting of the fingers of a user could expose the fingers to cuts from the blades as such a weapon is being used. This is a serious shortcoming with a weapon according to this teaching. The weapon taught by this patent also lacks a locking mechanism for retaining its blades in an extended position.
U.S. Pat. No. 2,741,025 to Stewart discloses a weapon having a pointed dagger element fixed orthogonal to a gripping member; and also having a tubular sheath of soft elastic material disposed around the dagger element, for protecting a user from the pointed dagger element in storage and for slidably exposing the dagger element in use as a weapon. This weapon does not have a blade. The use of a soft elastic sheath as taught by Stewart would be impractical with a knife blade having edges along the blade's length, because the sheath would be expected to be cut by the knife edges during handling and damaged, if pressure were brought to bear on the sides of the soft elastic sheath. Moreover, the use of a soft elastic material for a sheath around a knife blade would expose the fingers of a user to cuts if the fingers should push against the soft material. These are shortcomings for the weapon as taught by Stewart.
A need exists therefore for a knife with a blade that is orthogonal to its handle, and where the blade is also retractable. A need also exists for this blade to be easily retractable without binding of the retraction mechanism. A further need exists for a knife with such an orthogonal, retractable blade where the blade can be locked in an extended position. Still another need exists for a retractable blade knife where the blade will be enclosed while retracted to protect the user, and where the blade while extended will avoid having a cutting edge in close enough proximity to the fingers of a user to endanger the fingers.
As shown in A. G. Russell Catalog of Knives Spring 1999, p. 51, April, 1999, knives with blades having an irregular edge are known. Such blades appear to be made of materials that are easily fractured and flaked, such as flint or obsidian. These knives with an irregular edge have been used for many years and have been found particularly useful for cutting some materials. These knives have blades that lack certain strengths such as the ability to bend and cut without breaking across the width of the blade however. This lack of certain strengths is a serious shortcoming for the knives with flint or obsidian blades. A need therefore exists for a blade with an edge that is similar to an irregular edge, but that is made of a metal and that can be reproducibly manufactured.
To overcome such shortcomings, a blade edge is disclosed here that provides a cutting edge somewhat similar in appearance to the irregular edge used on flint or obsidian blades, but that is also suited for use with a metal knife blade.
To overcome the shortcomings of known knives above, and to satisfy the outstanding needs outlined above I have now discovered a new retractable knife. I have also discovered a new knife edge that can be used with the new retractable knife, or with other knives or other cutting implements.